From b7e589b98aa02f43af0f56e9a117a2e16af2b0c4 Mon Sep 17 00:00:00 2001
From: ChristophTobler <christoph.tob@gmail.com>
Date: Tue, 10 Oct 2017 17:51:56 +0200
Subject: [PATCH] EKF: only fuse optical flow if terrain is valid

---
 EKF/control.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/EKF/control.cpp b/EKF/control.cpp
index ac5ca71020..ed195e772a 100644
--- a/EKF/control.cpp
+++ b/EKF/control.cpp
@@ -383,8 +383,8 @@ void Ekf::controlOpticalFlowFusion()
 		_imu_del_ang_of += _imu_sample_delayed.delta_ang - _state.gyro_bias;
 		_delta_time_of += _imu_sample_delayed.delta_ang_dt;
 
-		// fuse the data
-		if (_control_status.flags.opt_flow) {
+		// fuse the data if the terrain/distance to bottom is valid
+		if (_control_status.flags.opt_flow && get_terrain_valid()) {
 			// Update optical flow bias estimates
 			calcOptFlowBias();